Search

Postural orthostatic tachycardia syndrome (POTS) is a complex multisystem disorder characterized by orthostatic intolerance and tachycardia and may be triggered by viral infection. Recent reports indicate that 2%-14% of coronavirus disease 2019 (COVID-19) survivors develop POTS and 9%-61% experience POTS-like symptoms, such as tachycardia, orthostatic intolerance, fatigue, and cognitive impairment within 6-8 months of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. Pathophysiological mechanisms of post-COVID-19 POTS are not well understood. Current hypotheses include autoimmunity related to SARS-CoV-2 infection, autonomic dysfunction, direct toxic injury by SARS-CoV-2 to the autonomic nervous system, and invasion of the central nervous system by SARS-CoV-2. Practitioners should actively assess POTS in patients with post-acute COVID-19 syndrome symptoms. Given that the symptoms of post-COVID-19 POTS are predominantly chronic orthostatic tachycardia, lifestyle modifications in combination with the use of heart rate-lowering medications along with other pharmacotherapies should be considered. For example, ivabradine or β-blockers in combination with compression stockings and increasing salt and fluid intake has shown potential. Treatment teams should be multidisciplinary, including physicians of various specialties, nurses, psychologists, and physiotherapists. Additionally, more resources to adequately care for this patient population are urgently needed given the increased demand for autonomic specialists and clinics since the start of the COVID-19 pandemic. Considering our limited understanding of post-COVID-19 POTS, further research on topics such as its natural history, pathophysiological mechanisms, and ideal treatment is warranted. This review evaluates the current literature available on the associations between COVID-19 and POTS, possible mechanisms, patient assessment, treatments, and future directions to improving our understanding of post-COVID-19 POTS.

BackgroundPostural orthostatic tachycardia syndrome (POTS), Ehlers-Danlos syndrome (EDS), and May-Thurner syndrome (MTS) are three syndromes that are often misdiagnosed or underdiagnosed. The true prevalence of these syndromes may be higher than currently reported. The following case series is the first to report a three-way association between POTS, EDS, and MTS.Case summaryWe describe three patients with concomitant POTS, EDS, and MTS. Although abdominopelvic vasculature evaluation can be difficult via conventional imaging techniques, we present the use of novel dynamic contrast-enhanced magnetic resonance angiography with Differential Subsampling with Cartesian Ordering (DISCO) and four-dimensional flow magnetic resonance imaging to aid vasculature evaluation and the diagnosis of MTS. Two patients underwent left common iliac vein stenting to treat MTS, experiencing significant improvement in their POTS symptoms and quality of life.DiscussionEhlers-Danlos syndrome, POTS, and MTS may interact synergistically to exacerbate symptoms. Patients with EDS should be evaluated for possible POTS and pelvic venous complications. Left common iliac vein stenting for MTS can mitigate POTS symptoms by decreasing lower extremity venous pooling and should be considered in this patient population. Further research is needed to understand the exact mechanism and intricacies of this syndrome triad.

Unmanned aerial vehicles (UAVs) can collaborate as teams to accomplish diverse mission objectives, such as target search and tracking. This paper introduces a method that leverages accumulated target-density information over the course of a UAV mission to adapt path-planning rewards, guiding UAVs toward areas with a higher likelihood of target presence. The target density is modeled using a Gaussian process, which is iteratively updated as the UAVs search the environment. Unlike conventional search algorithms that prioritize unexplored regions, this approach incentivizes revisiting target-rich areas. The target-density information is shared across UAVs using decentralized consensus filters, enabling cooperative path selection that balances the exploration of uncertain regions with the exploitation of known high-density areas. The framework presented in this paper provides an adaptive cooperative search method that can quickly develop an understanding of the region’s target-dense areas, helping UAVs refine their search. Through Monte Carlo simulations, we demonstrate this method in both a 2D grid region and road networks, showing up to a 26% improvement in target density estimates.

The Greenland Ice Sheet harbours a wealth of microbial life, yet the total biomass stored or exported from its surface to downstream environments is unconstrained. Here, we quantify microbial abundance and cellular biomass flux within the near-surface weathering crust photic zone of the western sector of the ice sheet. Using groundwater techniques, we demonstrate that interstitial water flow is slow (~10-2 m d-1), while flow cytometry enumeration reveals this pathway delivers 5 × 108 cells m-2 d-1 to supraglacial streams, equivalent to a carbon flux up to 250 g km-2 d-1. We infer that cellular carbon accumulation in the weathering crust exceeds fluvial export, promoting biomass sequestration, enhanced carbon cycling, and biological albedo reduction. We estimate that up to 37 kg km-2 of cellular carbon is flushed from the weathering crust environment of the western Greenland Ice Sheet each summer, providing an appreciable flux to support heterotrophs and methanogenesis at the bed.

Climate change-driven sea level rise and altered precipitation regimes are predicted to alter patterns of salt intrusion within the San Francisco Estuary. A central question is: Can we use existing knowledge and future projections to predict and manage the anticipated ecological impacts? This was the subject of a 2018 symposium entitled “Ecological and Physiological Impacts of Salinization of Aquatic Systems from Human Activities.” The symposium brought together an inter-disciplinary group of scientists and researchers, resource managers, and policy-makers. Here, we summarize and review the presentations and discussions that arose during the symposium. From a historical perspective, salt intrusion has changed substantially over the past 10,000 years as a result of changing climate patterns, with additional shifts from recent anthropogenic effects. Current salinity patterns in the San Francisco Estuary are driven by a suite of hydrodynamic processes within the given contexts of water management and geography. Based on climate projections for the coming century, significant changes are expected in the processes that determine the spatial and temporal patterns of salinity. Given that native species—including fishes such as the Delta Smelt and Sacramento Splittail—track favorable habitats, exhibit physiological acclimation, and can adaptively evolve, we present a framework for assessing their vulnerability to altered salinity in the San Francisco Estuary. We then present a range of regulatory and structural management tools that are available to control patterns of salinity within the San Francisco Estuary. Finally, we identify major research priorities that can help fill critical gaps in our knowledge about future salinity patterns and the consequences of climate change and sea level rise. These research projects will be most effective with strong linkages and communication between scientists and researchers, resource managers, and policy-makers.

Background: Immersive virtual reality (IVR) is utilized as an adjunct to anesthesia to distract patients from their intraoperative environment, thereby potentially reducing sedative and narcotic medication usage. This study evaluated intraoperative and acute postoperative results of patients undergoing primary total hip (THA) and total knee arthroplasty (TKA) with and without IVR. Methods: Utilizing IVR as an adjunct to spinal anesthesia, 18 primary THAs (n = 8) and TKAs (n = 10) were performed. These cases were 1:2 matched based on procedure type, age, sex, and body mass index to those performed without IVR. Intraoperative and postanesthesia care unit sedative/narcotic usage, vital signs, and pain scores were compared. Acute perioperative outcomes, including 24-hour oral morphine equivalent (OME), first ambulation distance, length of stay, and 30-day complications, were also analyzed. Pearson Chi-square and Wilcoxon-Mann-Whitney tests evaluated categorical and continuous variables, respectively. Results: When compared to non-IVR primary THAs and TKAs, those performed with IVR utilized significantly less intraoperative sedation (48 mg vs 708 mg of propofol; P < .001) and trended toward less narcotic usage (13 mcg vs 39 mcg of fentanyl; P = .07). In the postanesthesia care unit, IVR and non-IVR patients showed no significant differences (P > .3) in vital signs, pain scores, or OME received. Additionally, similar (P > .3) postoperative outcomes were noted in both cohorts’ 24-hour OME use, distance at first ambulation, length of stay, and 30-day complications. Conclusions: The use of spinal anesthesia with the IVR adjunct to perform primary THAs and TKAs appears to be well-tolerated and associated with less intraoperative sedative medication usage than spinal anesthesia alone.